Three months later, for my birthday, my parents' gift was a lizard – a bearded dragon. My parents had even gotten a terrarium with a layer of store-bought gravel, and my dragon looked happy to be sunning on the gray rock under the heat lamp. In a fit of giddy irony, I named her Clyde.

In the decades since the first rockets flew, the only launch vehicle capable of any kind of reuse was the Space Shuttle, which required in-depth inspection and refurbishment after each flight. Meanwhile, SpaceX and Blue Origin, among others, are revolutionizing the space launch industry and building rockets that can – and have – been reused. What's changed, and why is reusability coming back?